Oceanographic conditions in Galicia and the Southern Bay of Biscay and their influence on

the Prestige oil spill

M. Ruiz Villarreal, P. Otero, C. González Pola, A. Lavín, G. Díaz del Río and JM Cabanas

Instituto Español de Oceanografía

manuel.ruiz@co.ieo.es

Oil spill transport - Main driving agent was wind, but coastal circulation apparently has an impact in stranding points and affected area

- What is the fate of the fuel deposited at the bottom and fuel in the water column?

Impact on ecosystems- System subject to strong interannual variability. Difficult to ascribe an effect to the impact of oil spill. Conditions following spring are determinant for the response of the ecosystem

Oceanographic conditions during the Prestige oil spill: need for analysis

Historical IEO Demersales survey

Demersales0903Hidroprestige0303Accion Especial

Prestige

Historical IEO Pelacus survey

Prestige Plataforma1202

Prestige Plataforma0103

IEO Standard Sections

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1st Spring upw elling pulse

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Prestige trawl and spill

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Demersales02

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Summer 2002 to Autumn 2003

Upwelling index at 43N 11W

Salinity 100db Autumn 2002 Autumn 2003

Ruiz-Villarreal et al., Oceanographic conditions in Galicia and the Southern Bay

of Biscay and their influence on the Prestige oil spill, Submitted to MPB, 2005

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3 Poleward Slope current carrying subtropical watersDownwelling conditions

Poleward slope current

Freshwater plumes

Poleward current domain

River plumes

PLATERIAS project

Coastal circulation before stranding of 2nd spill

2nd spill drift simulation: wind + coastal circulation

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Upwelling index at 43N 11W

Spring transition in Galicia

Autumn-Winter

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at 5 dbar Geostrophic vel. at 5 dbar

- Upwelling pulses- Poleward current waters exported offshore during pulses- Eddy activity

- Freshwater plumes- Poleward current at the slope (warmer and saltier)

Garcia-Soto, Prestige oil spill and Navidad flow, JMBA, 2004

Santander slope Cantabrian. Intrusion of subtropical waters

Ruiz et al. Submitted to MPB, 2005

NCEP wind vector progressive diagram

Early commencement of spring in the Cantabrian Sea

Upwelling in the Cantabrian Sea during

Pelacus

December January

February March

MERCATOR-OCEAN PSY2 1/12º

mruiz:

Velocidad filtrada a un dia

mruiz:

Velocidad filtrada a un dia

Low passed filtered velocity (cm/s)

Galicia Bank

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Prestige wreck mooring

Conclusions- Circulation during Prestige accident:

- end autumn-winter situation. Shelf and slope intense circulation: river plumes, slope current

- more research needed on response of plumes and slope current to wind forcing (Platerias and Zotracos projects)

- propagation in the Cantabrian driven by the poleward current needs further analysis: poleward flow in December, but no signals of intrusion of subtropical waters

- Circulation during spring

- Cruises performed during “spring transition”: upwelling pulses influence circulation, poleward weakens and is exported offshore

- Early commencement of spring in the Cantabrian, and this could have affected ecosystem response

- Galicia Bank impact on circulation: tidal distortion, mesoscale activity… Further research is needed. Seamount ecosystem?